class IconCollector

class IconCollector extends CacheCollector {
    
    /**
     * Constructs a IconCollector instance.
     *
     * @param \Drupal\Core\Theme\Icon\IconExtractorPluginManager $iconPackExtractorManager
     *   The icon plugin extractor service.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache
     *   The cache backend.
     * @param \Drupal\Core\Lock\LockBackendInterface $lock
     *   The lock backend.
     */
    public function __construct(IconExtractorPluginManager $iconPackExtractorManager, CacheBackendInterface $cache, LockBackendInterface $lock) {
        parent::__construct('icon_info', $cache, $lock, [
            'icon_pack_collector',
        ]);
    }
    
    /**
     * {@inheritdoc}
     */
    public function set($key, $value) : void {
        $this->lazyLoadCache();
        $this->storage[$key] = $value;
        $this->persist($key);
        // Chances are very small but the key might have been marked for deletion.
        unset($this->keysToRemove[$key]);
    }
    
    /**
     * {@inheritdoc}
     */
    public function get($key, array $definition = []) : ?IconDefinitionInterface {
        $this->lazyLoadCache();
        if (\array_key_exists($key, $this->storage)) {
            return $this->storage[$key];
        }
        else {
            return $this->resolveCacheMiss($key, $definition);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function resolveCacheMiss($key, array $definition = []) : ?IconDefinitionInterface {
        $icon = $this->getIconFromExtractor($key, $definition);
        $this->storage[$key] = $icon;
        $this->persist($key);
        return $icon;
    }
    
    /**
     * Returns the icon from an icon id and icon pack definition.
     *
     * @param string $icon_full_id
     *   The icon full id as pack_id:icon_id.
     * @param array $definitions
     *   The icon pack definitions.
     *
     * @return \Drupal\Core\Theme\Icon\IconDefinitionInterface|null
     *   The icon loaded.
     */
    private function getIconFromExtractor(string $icon_full_id, array $definitions) : ?IconDefinitionInterface {
        $icon_data = IconDefinition::getIconDataFromId($icon_full_id);
        if (!isset($icon_data['pack_id'])) {
            return NULL;
        }
        $definition = $definitions[$icon_data['pack_id']] ?? NULL;
        if (NULL === $definition) {
            return NULL;
        }
        $icon_definition = $definition['icons'][$icon_full_id] ?? NULL;
        if (NULL === $icon_definition) {
            return NULL;
        }
        $icon_definition['icon_id'] = $icon_data['icon_id'];
        // Clean to data to reduce the array passed to createInstance().
        unset($definition['icons']);
        
        /** @var \Drupal\Core\Theme\Icon\IconExtractorInterface $extractor */
        $extractor = $this->iconPackExtractorManager
            ->createInstance($definition['extractor'], $definition);
        return $extractor->loadIcon($icon_definition);
    }

}